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题名	强震区宽级配粗粒土固结对泥石流发展趋势的影响
作者	高全
学位类别	硕士
答辩日期	2011-05-24
授予单位	中国科学院研究生院
授予地点	北京
导师	陈晓清
关键词	宽级配粗粒土 离心固结 三轴试验 泥石流发展趋势
其他题名	Influence of Wide Grading Coarsed Grained Soils’ Consolidation on Development Trend of Debris-flow
学位专业	防灾减灾工程及防护工程
中文摘要	5-12汶川地震诱发了大量的崩塌、滑坡等次生山地灾害，如北川魏家沟泥石流源头小型浅层崩滑体，为震后灾区泥石流的暴发提供了丰富的松散固体物源。野外考察发现，该类浅层滑坡的主要由宽级配粗粒土构成，故震后其强度的变化会影响源头崩塌滑坡的稳定性，进而会影响震后泥石流的发展趋势。另外，该类岩土体在自然界分布广泛，储量丰富，并具有压实性能好、透水性强、抗剪强度高、地震荷载作用下不易产生液化等优良工程特性，因此在工程建筑中得到广泛应用。如用于建筑高土石坝、高速铁路路基、桥梁墩台及处理软弱地基的砂石垫层等。因此，研究该类特殊宽级配粗粒土的物理力学性质、强度特征等具有一定的理论和实际意义。本文选取汶川地震强震区北川魏家沟源区浅层滑坡的宽级配粗粒土样，通过离心固结试验模拟震后土体的自然固结作用，并实施三轴剪切试验，探讨含水量、干密度及固结时间等参量对粗粒土应力-应变、强度等力学性质的影响，取得以下初步成果：（1）离心固结试验过程中，试样固结沉降量与时间呈正相关关系；固结时间相同时，试样最终沉降量随含水量增大逐渐增大，而随干密度增大逐渐减小，但增长或减小速度不同； （2）当含水量小于最优含水量时，围压对粗粒土强度的影响大于含水量的作用，此时围压占主导作用，而在高于最优含水量时，围压对粗粒土强度的影响逐渐减弱，水分对土体强度的影响占主导作用；粗粒土的粘聚力随含水量增大一直减小，而内摩擦角随含水量增大先增大后减小，在最优含水量附近达到最大值；（3）粗粒土的峰值抗压强度随干密度的增加显著增大，且在高围压下增长幅度更大；抗剪强度参数均随干密度增加而逐渐增大，但增长趋势存在差异。（4）相同含水量的粗粒土，离心固结1年时间后的峰值强度增大约12%-50%，固结3年时间后峰值强度增长约40%-96%；而相同围压下，固结时间为1年时，随着含水量的增大，峰值强度的增量逐渐减少，而当固结时间为3年时，情况正好相反（5）5-12汶川地震产生了包括崩塌、滑坡在内约27亿立方米的松散固体物质，为震后灾区泥石流的暴发提供了丰富的物质来源；震后3年内，随着松散固体物质的固结作用，强度会逐渐增大，泥石流会逐渐由输移控制型向松散固体物质控制型过渡。
英文摘要	5-12 Wenchuan Earthquake caused numerous secondary mountain hazards, including rockfalls and landslides, and wide grading coarsed grained soils (WGCGS) is the main composition of these landslides, like Weijiagou landslide, in Beichuan county, which provide sufficient materials for debris-flow. Therefore, the strength variation of coarsed grained soils can affect the stability of rockfalls or landslides, and also have a siginificant influential on the development of debris-flow in the disaster area. In addition, due to such advantages as good compaction, permeability and shear strength, and uneasy to liquefaction, WGCGS have been widely used in the construction of roadbed, pier, and especially earth and rockfill dam. Hence, mechanical and shear strength characteristics of WGCGS need to be discussed and studied. Some centrifuge consolidation tests and triaxial compression tests have been conducted and stress~strain and strength characteristics of WGCGS with different water content and dry density have also discussed in this paper, form which some research results can be shown as follows: (1) Consolidation settlement amount has a positive correlation with time in the process of contrifuge tests, and the settlement increases with the increment of moisture content, but decreases with the increment of dry density under the same consolidation time. (2) When water content is less than optimal moisture content, the strength of WGCGS can be more determined by confining pressure than water content; with the increment of moisture content the role of confining pressure can be weaken, that is, water have a greater effect on the strength of WGCGS, when water content is more than optimal moisture content. Compared with cohesion’s increment, internal friction angle of coarsed soils increases firstly and when desreases when water content is more than optimal moisture content. (3) The peak compression and shear strength of WGCGS increases with the increment of dry density, particularly in the high confining pressure, but with different speed; (4) The peak compression strength of wide grading coarsed graned soils can increase by 12~50% after 1 year consolidation and 40~96% after 3 year consolidation with the same moisture content; after 1 year consolidation under tha same confining pressure . (5) Nearly 270 million loose solid materials in meizoseismal area are caused by 5-12 Wenchuan earthquake, rock-fall and landslide included, which is beneficial for debris-flow; due to consolidation of wide grading coarsed grained soils in source region of debris-flow, shallow landslide could be more stable than it ever before, and debris-flow could translate from transport-limited type to transport- or weathering-limited transitional type.
语种	中文
公开日期	2013-01-25
内容类型	学位论文
源URL	[http://192.168.143.20:8080/handle/131551/4843]
专题	成都山地灾害与环境研究所_山地灾害与地表过程重点实验室
推荐引用方式 GB/T 7714	高全. 强震区宽级配粗粒土固结对泥石流发展趋势的影响[D]. 北京. 中国科学院研究生院. 2011.

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